MadMonkey: I'm not sure I like that.
One of the main reproaches against MS is that they always try to build "the program of everything", which looks fine as an idea, until you realise that:
- it is impossible to have only the parts you want, you get (and will have to use) everything or nothing.
- if one thing doesn't work (and which program is bugfree?) nothing does.
And Mozilla, apparently, is following the same glorious path. What could possibly be the advantage of combining those two distinct functions (browsing and email management) in a single program?

As for thunderbird, I myself have practically no more use for it, with webmail servers such as yahoo or google offering unlimited space and fast access. I use it almost exclusively to browse newsgroups.